Resins - Natural Resins, Thermosetting Resins - Synthetic resins, Thermoplastic resins
Historically, the term resin has been applied to a group of substances obtained as gums from trees or manufactured synthetically. Strictly speaking, however, resins are complex mixtures, whereas gums are compounds that can be represented by a chemical formula.
The word gum was originally applied to any soft sticky product derived from trees; for example, the latex obtained from Hevea trees, which is the source of natural or gum rubber. Natural rubber, i.e, chemically unsaturated polyisoprene, is a polymeric material that can also be produced synthetically. (A polymer is a macromolecular compound made up of a large number of repeating units,
|Synthetic Resin||1994 U.S. Sales (in million of pounds)||Major Applications|
|phenolics||3222||electrical products such as ovens and toasters, wiring devices, switch gears, pulleys, pot and cutlery handles|
|unsaturated polyesters||1496||construction and transportation industries|
|polyurethanes||1102||building insulation, refrigeration|
|amino resins||2185||wiring devices, molded products, electrical parts, adhesives and bonding agents|
|epoxy resins||602||coatings, reinforcement, electrical and electronic applications, adhesives, flooring, and construction|
|galbanum||gum resin from perennial herb of western Asia||medicinal uses|
|myrrh||gum resin from small trees of India, Arabia, and northeast Africa||incense and perfumes; medicinal tonics, stimulants, antiseptics|
|asafetida||gum resin from perennial herb||Asian food flavoring; used for medicines and perfumes in the United States.|
|creosote bush resin||amber-colored, soft, and sticky gum resin from the leaves of the greasewood bush or creosote bush of the desert regions of Mexico and the southwestern United States||adhesives, insecticides, core binders, insulating compounds, pharmaceuticals|
|okra gum||gum resin from the pods of a plant native to Africa but now grown in many countries||foodstuffs, pharmaceuticals; used for its antioxidizing and chemically stabilizing properties, and as a gelation agent|
|ammoniac resin||gum resin from the stems of a desert perennial plant of Persia and India||adhesives, perfumes, medicinal stimulants|
|Synthetic resin||1994 U.S. Sales (in million of pounds)||Major applications|
|polyethylene||25,683||packaging and non-packaging films|
|polypropylene||9752||fibers and filaments|
|polystyrene||5877||molded products such as cassettes, audio equipment cabinets; packaging film; food-stock trays|
|acrylonitrile/butadiene/styrene (ABS)||1489||injection-molded automotive components|
|polyethylene terephthalate (PET)||—||food packaging|
|polyvinyl chloride||11,123||flooring; pipes and conduits; siding|
|polycarbonate||695||compact discs and optical memory discs|
|nylon||921||transportation industry products|
|thermoplastic elastomers||867||automotive, wire and cable, adhesive, footwear, and mechanical goods industries|
|liquid crystal polymers||—||chemical pumps, electronic components, medical components, automotive components|
|acetals||214||transportation industry products|
|polyurethane||1790||flexible foams in the transportation industry|
|thermoplastic polyester||3441||engineering plastics|
called mers.) Thus, although the term resin when applied to polymers actually antedates the understanding of the chemistry of polymers and originally referred to the resemblance of polymer liquids to the pitch on trees, it has by association also come to refer to synthetic polymers.
Synthetic resins are polymeric materials, which are better known as plastics. The term plastic better describes polymeric material to which additives have been added. There are two important classes of synthetic resins: thermosetting resins and thermoplastic resins.
Thermoplastic resins are polymeric materials that can be softened and resoftened indefinitely by the application of heat and pressure, provided that the heat that is applied does not chemically decompose the resin. Table 3 lists some commercially important synthetic thermoplastic resins, their uses, and their levels of consumption.
Brady, G. S., and H.R. Clause. Materials Handbook. New York: McGraw Hill, Inc. 1991.
Engineered Materials Handbook. Metals Park, OH: ASM International, 1988.
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